I think I well past the point of being a pest with this thread so I guess I may as well go for broke.
To better understand the running (parking) light circuit and the signal circuit I sketched them from ERAs wiring diagram.
When I install LED in both rear lights the following happens:
Parking Lights - OFF, but Ignition ON
Turn Signal turned on.
All four corner lights flash and the license plate light. I can see that on the side the turn signal is turned on - the parking light and flasher led elements are ALL flashing. On the opposite side, ONLY the parking light led elements are flashing (not the turn signal ones).
Not sure on the front but I think both filiments on the side with the turn signal on are flashing and on the opposite side the parking light filiment is flashing.
So . . . the puzzle is how is power getting to the parking light circuit with the parking lights off? The parking light and turn signal light circuits are pretty separate and I can't see where they could be cross-talking by a relay or something.
Parking lights (and license light) are all tied together and come off of the #6 fuse which is fed by the light switch and in turn fed from the ignition switch.
As far as I can understand the turn signals draw power from the #4 fuse to the flasher unit and then to the turn signal switch.
When I tried to test LED bulbs for continuity I got nothing so they are kind of like relays and have to be fed power. In my not-electical circuit oriented mind it seems like the bulb internals must be leaking power from the turn signal cirucit to the parking light circuit and back feeding it.
I did try to remove a sigle bulb at a time to see what happened but the results were what is expected. Side with bulb removed didn't flash but the other side did.
Thoughts Patrick?
Edit: I forgot to mention that when I turned the parking lights ON with LEDs in place - all lights and signals worked 100% correctly.